Hello Tiju,
Thanks for the report.
I noticed that the pin_mux component is missing a pin direction setup.

please adjust ENET0 RMII Transmit Clock pin as output and regenerate code:

Now you should be able to build and debug the project.
Regarding the C errors in Problem View -> this is a known eclipse issue, please try the workaround described here:
https://community.nxp.com/message/924323#comment-924619
Note: Before pinging the DevKit don't forget to update the ARP table on your PC manually. This example does not process ARP request packets.
Hope it helps.
Stan